The present invention relates to solenoid operated valves and particularly valves of the type where an armature is disposed within the coil with an operating member for contacting and moving a valving element. Solenoid operated valves of the aforesaid type typically utilize an armature disposed within the coil forming an axial working air gap between the armature and the stationary pole piece or flux collector; however, an annular air gap is also formed about the armature by virtue of the arrangement of the armature within the coil.
Where a solenoid armature is disposed within the coil, any eccentricities or off center disposition of the armature will result in a reduced radial air gap on one side of the armature. This eccentricity inherently increases the magnetic flux across the narrowest part of the gap creating an imbalance and consequently increases the radial or side loading on the armature which can result in increased friction and resistance to axial armature movement in response to coil energization.
Heretofore, efforts to control the eccentricity of the annular air gap about a solenoid armature disposed within a coil have required tight control of tolerances on the manufacturing of the armature and the flux collector and a loss of the sliding bearing surfaces for positioning the armature within the coil, which has significantly increased the cost of manufacturing of the solenoid valve. Accordingly, it has been desired to provide a way or means of reducing the eccentricity of the annular air gap about an armature within the coil of a solenoid operated valve and to do so in a manner that is simple and relatively low in manufacturing cost thereby making the value suitable for high volume production of applications such as those employed for control functions in automotive applications.